TECHNICAL FIELD OF THE INVENTION

This invention relates to machines for non-abras i ve ly peeling onions or other fruits or vegetables such as pineapples or scallions which can be peeled in simi lar manne r .

BACKGROUND OF THE INVENTION

In an existing machine which is described in UK Patent Specification No. 2 151 129 A, onions are fed one-by- one to a pair of rotating drums which support and spin the onion. After a predetermined period of time a blast of compressed air is directed onto the spinning onion to remove its skin, and the drums then move apart allowing the peeled onion to drop through. Since the onions are only peeled one at a time this machine has a very low peeling rate. The use of an air compressor also results in high operating cost.

UK Patent Specification No. 1 393 990 describes a peeling machine comprising a pair of parallel rotatable shafts for supporting and spinning the onions, with a stop plate located above one of the shafts and a number of water sprays located above the other shaft spaced along its length. A conveyor carrying a series of spaced fingers moves the onions progressively along the shafts through the water sprays to remove their skins. Although this machine has a higher handling rate, it is

of relatively complex construction and can only handle onions within a restricted size range.

SUMMARY OF THE INVENTION

In the present machine the onions are again supported by a pair of rotatable shafts and a peeling jet of fluid (e.g. air) is directed into the onions to remove their skins. However, the onions are conveyed along the shafts by a helical screw carried by one of the shafts which constitutes a conveyor shaft, and the other shaft constitutes a spinner shaft for spinning the oni ons .

The spinner shaft wi ll normally rotate at several times the speed of the conveyor shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention wi ll now be exemplified in the following description to be read in conjunction with the accompanying drawings in which:

Figure 1 is a side view of an onion peeling machine in accordance with the invention.

Figure 2 is a plan view of the machine, and

Figure 3 is an end view of the machine looking from the right in Fig.s 1 and 2.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

The machine comprises a pair of shafts 1, 2 rotatably journalled in bearings 3, 4 respectively (Fig. 2), which are in turn mounted on a frame 5. The first shaft 1 constitutes a spinner shaft having a knurled surface, but it could also be smooth or rubber-coated. The other shaft 2 consitutes a conveyor shaft and carries a helical screw 6 in the form of a radially projecting blade which extends along the length of the shaft. The two shafts are mounted on substantially parallel axes, side-by-side, with the outer periphery of the screw 6 almost, but not quite, touching the spinner shaft 2. The shafts together form a channel 7 in which an onion can be supported by the two shafts.

The shafts are each rotatably driven from a respective variable speed motor 8, 9 (e.g. an electric or petrol driven motor) via a belt and pulley, chain and sprocket or simi lar drive system 10, 11.

At one end of the channel 7 (the left hand end as shown) a chute 12 is mounted on the frame 5 to feed top-and-tai led onions (i.e. onions having their tops and root ends sliced off) one after another to the shafts. The chute is downwardly inclined to direct the onions into the left hand end of the channel 7. An air driven vibrator 16 is mounted on the underside of the chute to assist in moving the onions along the chute. An air driven motor 17 is also mounted on the underside of the chute to drive a set of rotating circular blades 18 (e.g. four) mounted on a common axis disposed transverse to the chute. The blades are arranged such that they project an adjustable distance above the floor of the chute.

Towards the right hand end of the channel 7 a nozzle 20 (Fig.s 1 and 3) is mounted by a sliding clamp 21 on a pole 22 which is upstanding from the frame 5. The nozzle is directed downwardly through the gap between the shafts. The opening of the nozzle is slot-shaped and is aligned with the axes of the shafts 1, 2, although the nozzle could also be inclined at an acute angle to the axes of the shafts. The nozzle is connected by a suitable wide bore flexible pipe 24 to an air blower 25 (Fig. 3) for supplying a continuous low pressure air jet through the nozzle 20.

At the right hand end of the channel (see Fig.s 1 and 2), an outlet chute 26 is mounted on frame 5 to collect the onions as they drop off the ends of the shafts.

A funnel 28 (Fig.s 1 and 3) is arranged beneath the shafts to collect onion skins, which are then carried away to waste by a conveyor 29.

In use, the shafts are set to rotate at speeds of typically 700 rpm for.the spinner shaft and 130 rpm for the conveyor shaft. Both shafts rotate in the same direction A (Fig. 3). Contra-rotating shafts may also be used but this would tend to cause the onions to jump around in the channel. Top and tailed onions are fed along the vibrating chute 12 to the shafts 1, 2 where they arrive in random orientations. The distance by which the blades 18 project above the chute floor is adjusted to nick the outer skins of the onions as they pass along the chute, to make removal of the skins easier. The baldes may not be necessary for some kinds of onion, particularly those with thin skins. The onions are then conveyed along the channel 7 one-by-one

separated by the screw 6 and supported by both shafts 1 and 2. The leading radially extending face of the screw 6 positively urges the onions along the shafts, and as the onions travel towards the nozzle 20 the rotation of shaft 1 starts the onions rotating. The onions initially spin slowly about random axes but as they travel along the channel their rotational speed increases and they eventually come to rotate about a natural axis of rotation which, if the onion is perfectly symmetrical, is coincident with its axis of symmetry. When an onion reaches the nozzle 20 the air jet blows its skin off. The loose skins are blown through the gap between the shafts into the funnel 28 but the onion continues to the end of the shafts and thence to the outlet chute 26.

The speeds of the shafts can be independently adjusted to values most appropriate for a particular batch of onions to ensure thorough peeling without removing too many layers from their skins. The height, and thus the jet intensity, of the nozzle can be adjusted by sliding clamp 21 along pole 22. The conveyor shaft 2 can be replaced with one of different shaft and/or screw diameter and pitch to suit different sizes of onion. Thus, the machine can easi ly be adapted for peeling onions from shallot size up to Spanish onion size and with different thicknesses and toughness of skin. The spacing betwen the shafts could also be made adjustable if desired.

The hopper 28 and conveyor 29 could be replaced with a chute along which the onion skins are blown by the jet from nozzle 20. The slot-shaped nozzle could also be replaced with a row of individual jet openings.

Although the machine is essentially non-abrasive it would be possible, within the scope of the invention, to provide one or both of the shafts 1, 2 with an abrasive surface to assist in removal of the skins, as long as the main peeling action was by the fluid jet.

The use of a blower instead of a compressor can reduce the energy consumption of the machine by as much as two thirds. In addition, the machine has a high rate of handling, requires little maintenance and is easy to c lean.